Catalytic process for the polymerization of olefins



United States Patent U.S. Cl. 260-949 3 Claims ABSTRACT OF THEDISCLOSURE Polyolefins are prepared by polymerizing an olefin in thepresence of a catalyst. The catalyst is a mixture of a halide of Ti, Va,or Zr and an organo-titanium compound. The organo-titanium compound hasthe formula wherein R is an alkyl group and Z is (CH m being 2, 3 or 4.

This invention relates to a process for producing polyolefins bypolymerizing olefins in the presence of a catalyst prepared from a metalhalide and a novel organo titanium compound. Further, the inventionpertains to a process for producing polyolefins in which theabovementioned catalyst is incorporated with a dialkylzinc and an amineto form a new catalyst system convenient for the production ofpolypropylene and in which any of the above-mentioned catalysts is usedin the presence of hydrogen to modify the molecular weight of theresulting polyolefins.

As a process for polymerizing olefins using a polymerization catalystcontaining a titanium compound as one component, there is already knowna process in which there is used a catalyst obtained from titaniumtetrachloride or titanium trichloride and an organo aluminum compound.

As a result of various studies, the present inventors have discovered anovel polymerization process in which olefins are highly polymerizedwith favorable efficiency without using any organo aluminum compound.

The organo titanium compound, which is one component of the catalystemployed in the present invention, is a titanium compound having analkyl group in the molecule. Even when an organo titanium compoundhaving such an alkyl group in the molecule is used independently, it ispossible to polymerize ethylene. In this case, however, not only hightemperature, high pressure and a long period of time are required, butalso the catalyst should be used in a large amount, and therefore thepolymerization efficiency is markedly poor. In the case of propylene andthe like olefins, substantially no polymers can be obtained by theindependent use of such organo titanium compound.

The inventors have found that a catalyst system prepared by adding ametal halide to said organo titanium compound shows a highpolymerization activity, under extremely mild polymerization conditions,towards olefins such as ethylene, propylene, l-butene, l-pentene,styrene, butadiene, isoprene, chloroprene and the like, and that it canpolymerize ethylene to polyethylene which is high in bulk density (0.25O.35 g./cc.) and propylene ICC and the like olefins to polymers with ahigh degree of stereospecificity.

As the metal halide, which forms one component of the above-mentionedcatalyst, any of the halides of titanium, vanadium and zirconium isusable. These metal halides include, for example, titanium trichloride,titanium tetrachloride, vanadium tetrachloride, vanadium trichloride,vanodiaum dichloride, vanadium oxychloride, zirconium tetrachloride andbromides and iodides of said metals. Particularly in the case oftitanium trichloride, there may be used the so-called A or H type whichare respectively prepared by reducing titanium tetrachloride withaluminum or hydrogen.

The organo titanium compound, which is the other component of thecatalyst, is a compound represented by the general formula zlz, ZM(CH2)4, 3) 2 2 C(CH CH CH(CH and CH(C3H7)CH(C2H5)CH2 is preferable fromthe viewpoints of preparation and handling. Considering the above, theorgano titanium compounds particularly eifective as CH2 O-CHCfia(hereinafter referred to as PDTDM) and (hereinafter referred to HDTDM).These organo titanium compounds can be obtained by reacting at 70 C. to20 C., in the presence of an organic solvent such as ether ortetrahydrofuran, a titanium dihalide of the formula XzTi z wherein X isa halogen atom; and Z is as defined above, either with a Grignardreagent 0f the formula RM X, wherein X is a halogen atom, or with analkylmagnesium of the formula R Mg, removing the solvent under reducedpressure and then extracting and purifying the residue with ahydrocarbon solvent such as pentane or heptane. The abovementionedtitanium dihalide of the formula XZT 2 can be prepared either by thereaction of a titanium tetrahalide with a diol of the formula HOZOH,wherein Z is as defined above, or by the reaction of a titaniumtetrahalide with 2 1 titanium compound of the formula V i o wherein Z isas defined abovei A catalyst showing a particularly high activity in thepolymerization of ethylene is the mixture of titanium tetrachloride,titanium trichloride, vanadium tetrachloride, vanadium trichloride orvanadium oxychloride vanadiurn trichloride or vanadium oxychloride withPDTDM or HDTDM.

A particularly excellent catalyst for the polymerization of propylene isthe mixture of titanium trichloride with PDTDM or HDTDM.

Polymerizable olefins include hexene and vinyl'cyclohexane and the likein addition to those mentioned above. In the present invention, not onlycan said olefins be homopolymerized, but also 2 or more olefins can becopolymerized. For example, a catalyst comprising vanadium tetrachlorideand PDTDM can copoiymerize ethylene with propylene to forth a rubberysubstance. 7

In the polymerization according to the present invention, an aliphatichydrocarbon such as hexane, heptane, octane, or cyclohexane, or anaromatic hydrocarbon such as benzene, toluene or xylene, may be used asapolym; erization solvent. It is also possible to use a liquid olefin asa polymerization medium without using any of the above hydrocarbons assolvent. In such a case, the polymerization rate particularly increasesas compared with the case where said hydrocarbon solvent is used; andtherefore the polymerization may be effected either at atmosphericpressure or under pressure. Polymerization temperature is to 100 0.,preferably 60 to 80 C.

The metal halides can be used not only independently but also as amixture of 2 or more. The molar ratio of the metal halide to the organotitanium compound employedin the polymerization is preferably within therange of from 1:0.5 to 154. I

Specifically, the polymerization in accordance with the present processis carried out in the following manner:

In an atmosphere of an inert gas such as nitrogen or argon, ahydrocarbon solvent, a metal halide and an organo titanium compoundarercharged into an autoclave or asimilar polymerization reactor. Themixture is heated, if necessary, to above room temperature to activatethe catalyst. Subsequently, an olefin is added thereto and ispolymerized with stirring, and the mixture is maintained at a givenpolymerization temperaturefAfter the polymerization, the catalyst isremoved by a decomposition treatment with an alcohol oralcohol-hydrochloric acid solution, and the resulting polymer is dried.In place of adopting such a batch-wise manner, the ,polymerization maybe effected in a continuous manner, as well. 7 The polyethylenesprepared according to the present process are high in density, and areindustrially useful materials which ean be applied, like otherpolyolefins, to the production of various shaped articles, syntheticfibers and films. However, polyethylene differs in moldability and inuses of products obtained therefrom, depending on the molecular weightthereof, and therefore the availability of polyethylene having variousmolecular weights is desirable. l

The present inventors have now found that when a suitable amount ofhydrogen is introduced into the abovementioned polymerization system,the molecular weight of the resulting polyethylene can be optionallymodified, That is, in case any of the aforesaid catalyst systems is usedindependently, the molecular weight of the resulting polyethylene easilyexceeds 1,000,000, but when hydro;- genf is introduced, the molecularweight can be arbitrarily modified to several tens of thousands whichvalue is the most practical. n 1

As to polypropylene, on the other hand, the inventors have found thatwhen a dialkylzinc is furtheradded to theaforesaid catalyst, thecatalyst activity (hereinafter referred to *as C.Ar) can be rapidlyincreased. The C.A. is defined herein as the amount t g.) ofpolypropylene formed per hour per gram of titanium trichloride.

Table l below shows examples of propylene polymerization using aliquefied propylene without using solvent. It is seen from the tablethat as compared with the case of a catalyst system comprising onlytitanium trichloride and an organo titanium compound, the C.A. of acatalyst system prepared by adding to said catalyst system diethylzincas a dialkylzinc is more than 10 times the C.A. of said catalyst system,cf. Example 2 in the table. This is of great value, since incornmercial'production, a large amountpf polymer can be obtained by useof a small amount of catalyst.

7 'TABLE 1 Example 1 2 3 4 Titanium trichloride (rnrnolJ 0.5 0. 5 0. 50. 5 Organe titanium compound 2 PDTDM (mrnoL) 0 5 0.5 0.5 0.5Diethylzinc (mmol.) 0 0.75 0.75 0. 75 Triethylamine (rnrnoL) 0 0 0. 750.75 Hydrogen (moL) 0 0 0 0. 00? C.A 78 860 650 520 Molecular weight X104 71 1e 4 55x10 4 16 10 4 1.1. (percent) 56 89 86 1 Isotacticity index,i w 1) 2 0-o (CHgQgTl 2011.

Another favorable advantage of ire use of diethylzinc is in that itlowers .the molecular weight of polypropylene. Thus, the addition ofdiethylzinc is markedly effective in increasing catalyst activity and inlowering the molecular weight, but has such a drawback as to bring abouta lowering of the LL of the polymer. The H. is a value showingithecontent of isotactic structure which, practically, is the most favorablein property as the stereospecific structure portion in polypropylene. Itis known that the greater the isotacticity, the more excellent the resincharacteristics and the more advantageous the production ofpolypropylene. The value of 1.1. is given as the percentage of hotheptane-insolubles present in the polypropylene. T

in order to prevent the polypropylene from undergoing a lowering in1.1., we have investigated various additives and found that amines areeffective therefor. That is, when triethylamine is added as the amine,the 1.1. of the polymer greatly increases, as seen in Example 3 ofTable 1. Other amines also show the same effects as above.

Further, in order for polypropyiene to be practically useful, it isrequired that it be excellent in mechanical characteristics andprocessability. For this; the polypropylene should have a properlycontrolled molecular weightf lt has been known that the practicalmolecular weight of polypropylene is from about 130,000 to 230,000. Wehave made various examinations of molecular weight modifiers and foundthat the use. of hydrogen is effective. Table 1 shows in Example 4 theresults attained by the use of hydrogen.

As the aforesaid dialkyzinc, diethylzinc is particularly effective.Further, as the amines, various aliphatic or aromatic amines may be usedbut, in particular, trethylamine gives favorable results.

When the catalyst components employed are represented by molar ratio,the ratio of ;titanium trichloride:organo titaniumcompound:dialkylzinczamine is preferably Within the range of1:(0.5-3):(0.5-4):(0.1-6). The increase in the amounts of orgaaiotitanium compound and dialkylzinc has a tendency to increase thecatalyst activity and the 'increase in the amount of amine hasaatendency to increase the 1.1. Further, the increase in the amount ofhydrogen is effective in lowering the molecular weight. When hydrogen isused in an amount of to 1500 p.p.m. based on liquefied polypropylene,the molecular weight of the resulting polymer can be effectivelymodified.

The following examples illustrate the invention.

(I) PRODUCTION OF ORGANO TITANIUM COMPOUNDS Example Il In a 300 ml.three-necked, round-bottomed flask, 2.98 g. (25.2 mmol.) of2-methylpentane-2,4-diol,

was dissolved in 150 ml. of anhydrous ether.

To the solution, 4.85 g. (25.5 mmol.) of titanium tetrachloride wereadded dropwise, while vigorously stirring the solution in an argonatmosphere, and the stirring was continued until all of the yellowprecipitates became white. Subsequently, 1180 ml. (50.4 mmol.) of driedammonia gas were injected into the mixture and were combined withby-product hydrogen chloride to complete an equilibrium reaction.Thereafter, the reaction mixture was cooled to 10 C., and 57.4 ml. (63.2mmol.) of an ether solution of methylmagnesium chloride were addeddropwise thereto over a period of 1.5 hours. Immediately aftercompletion of the dropwise addition, the reaction mixture was filtered,and filtrate was concentrated at 0 C. under reduced pressure and wasfinally dried at 20 C. under 1 mm. Hg for one hour to completely removethe ether. The resulting greyish yellow powder was extracted with 280ml. of pentane to obtain 278 ml. of a light yellow transparent solution.This solution had a titanium concentration of 0.051 mmoL/ml. and theyield thereof was 56% (based on Ti; the same shall apply hereinafter). Apart of the solution was recrystallized at 78 C. or was concentrated todryness, and the resulting light yellow crystals were analyzed toconfirm that the product was a dimer of 2-methylpentane-Z,4-diol-titanium-dimethyl l CH3 2 having a titaniumcontent of 24.60% (theoretical value: 24.67%) and a molecular weight(according to freezing point depression method using benzene) of 392(theoretical value: 388.2).

Example I-2 bottomed flask, and was dissolved in 1 l. of anhydroustetrahydrofuran. To the solution, 114 ml. (257 mmol.)

of an ether solution of methylmagnesium iodide were added dropwise overa period of 23 hours, while vigorously stirring the solution at 10 C.After completion of the dropwise addition, the mixture was furtherstirred at 10 C. for an additional hour, mixed with 500 ml. of cooledpentane and then allowed to stand. Subsequently, the liquid portion wasseparated and was concentrated to dryness at 10 C. under reducedpressure, and the resulting residue was extracted with 600 ml. ofpentane. The extract was cooled overnight at -78 C. to obtain 14.4 g.(74.3 mmol.) of light yellow crystals, yield 58%. The thus obtainedproduct was substantially identical with the product obtained in ExampleI-l.

Example I3 6.76 g. (32.6 mmol.) of a white powder of OCH2 OlzTl CH2which had been obtained by reacting in benzene or the like oCH,

with an equivalent of titanium tetrachloride, was suspended in 500 ml.of anhydrous tetrahydrofuran in an argon atmosphere. To the suspension,29.2 ml. (65.2 mmol.) of an ether solution of methylmagnesium iodidewere added dropwise over a period of one hour, while vigorously stirringthe suspension at 10 C. After completion of the dropwise addition, thesuspension was further stirred at 10 C. for 3 hours, mixed with 200 ml.of cooled pentane and then allowed to stand. Subsequently, the liquidportion was separated, concentrated to dryness at 10 C. under reducedpressure, and the resulting residue was extracted with 200 ml. of cooledpentane. The extract was cooled overnight at 78 C. to obtain 0.83 g. (5mmol.) of yellow crystals, yield 15%. The crystals were analyzed toconfirm that the product was a dimer of butane-1,3-diol-titaniumdimethyl (CH3)2Ti OCH (II) POLYMERIZATION OF OLEFINS BY USING ORGANOTITANIUM COMPOUND-METAL HA- LIDE CATALYST SYSTEM Example 11-1 A 200 ml.autoclave was thoroughly flushed with argon, and was charged with 10 ml.of a pentane solution containing 0.075 g. of titanium trichloride and0.194 g. of PDTDM. The autoclave was cooled to below room temperature,and 67 g. of liquefied propylene were added to the pentane solutionunder pressure. Subsequently, the mixture was heated and polymerizedwith stirring at 70 C. for one hour. The resulting polymer was treatedwith methanol and was then dried to obtain 18.7 g. of a white powderypolypropylene. The polymer had a heptane insoluble content of and anintrinsic viscosity [1;] of 14.6 (measured in tetraline at C.; the sameshall apply hereinafter).

Example II-2 Polymerization was effected in exactly the same manner asin Example II-l, except that 0.097 g. of PDTDM was used, to obtain 5.2g. of a polypropylene having a hot heptane insoluble content of 87% andan intrinsic viscosity [7 of 15.3.

7 Example 11-3 A 200 ml. of autoclave was thoroughly flushed with argon,and was charged with 95 ml. of a heptane solution containing 0.075 g. oftitanium trichloride and at 70 C. for one hour. The resulting polymerwas treated with methanol and was dried to obtain 13.3 g. of a rubberypolymer.

(HI) POLYMERIZATION OF ETHYLENE BY USING 0.194 g. of PDTDM. Theautoclave was cooled to be- ORGANO TITANIUM COMPOUND-METAL HA- low roomtemperature, and liquefied propylene was add- LIDE-HYDROGEN CATALYSTSYSTEM ed to the heptane solution under pressure. Subsequently, themixture was heated and polymerized with stirring Examples HI 1 to at 70C. for one hour while maintaining the pressure A 1000 rnl. autoclave Wasfl hed w h a g a Was at 11 kg./cm. The resulting polymer was treatedwith charged W1th 500 ml. of heptane and the amounts of methanol and wasthen dried to obtain 6,1 g, of a polytitanium tetrachloride and PDTDMgiven in Table 2. propylene having a hot heptane insoluble content of89%, Subsequently, the liquld in the autoclave was maintained and anintrinsic viscosity of 11.1, at 50 C. or 60 C., and ethylene pressurizedto 9 E am 1 H4 kg./crn. was absorbed in the liquid with stirring until Xp e the ethylene pressure became 8.8 kg./cm. After dis- A 1000 ml.autoclave was thoroughly flushed with archarging ethylene, a mixed gascomprising ethylene and gon, and was charged with 500 m1. of a heptanesoluhydrogen in a definite proportion was charged under tion containing0.072 g. of titanium tetrachloride and pressure into the liquid, and themixture was polymerized 0.145 g. of PDTDM. Into the heptane solution,ethylene for a definite period of time. After the polymerization, wasintroduced under pressure, and the mixture was heatthe resulting polymerwas treated with methanol and was ed and polymerized at 70 C. forminutes while mainthen dried to obtain powdery polyethylene. The resultstaining the pressure at 10 kg./cm. The resulting polyare shown in Table2.

TABLE 2 Example 1 2 s 4 5 s 7 s 9 10 11 12 1 1 1 1 1 1 1 1. 0 1. 33 0.82 i 2 2 2 2 2 2 2 2 2 2 2 .3 3 Ethylene pressure 3 3 3 3 3 3 3 2 2 2 2 2Hydrogen pressure (kg/0111. 15 3 6 7. 5 6 6 6 4 4 4 4 4 Polymerizationtemperature so 00 so 00 50 50 50 50 50 50 Polymerization time (min.) 210210 210 210 90 120 210 00 00 90 120 120 Polyethylene (g.) 106 102 04 6083 96 93 42 .52 33 Molecular weight 7. 7x10 53x10 4.0)(10 214x10 5.5)(105.5x10 5. 0 1m 51x10 8.6X10* x10 s.7 10 7.5 10

vanadium tetrachloride. 2 Zirconium tetrachloride.

mer was treated with methanol and was then dried to 35 (IV)POLYMERIZATION OF PROPYLENE BY US- obtain g. of polyethylene powder.

Example II5 A 3000 ml. autoclave was flushed with argon, and was chargedwith ml. of a heptane solution containing 0.28 g. of zirconiumtetrachloride and 0.23 g. of PDTDM. Into the solution, ethylene wasintroduced under pressure, and the mixture was heated and polymerizedwith stirring at 70 C. for one hour while maintaining the pressure at 10kg./cm. The resulting polymer was treated with methanol and was thendried to obtain 10.3 g. of polyethylene powder.

Example 11-6 A 300 ml. autoclave was flushed with argon, and was chargedwith 150 ml. of a heptane solution containing 0.13 g. of titaniumtetrachloride and 0.27 g. of PDTDM. To the heptane solution, 25 g. ofbutene-l was added, and the mixture was heated and polymerized withstirring at ING ORGANO TITANIUM COMPOUND-TITANI- UM TRICHLORIDEDIALKYLZINC-AMINE-HY- DROGEN CATALYST SYSTEM Examples IV-l to 11 A 300m1. autoclave was thoroughly flushed with argon and was charged with theamounts of titanium trichloride, PDTDM as organo titanium compound,diethylzinc and triethylamine given in Table 3. Into the autoclave, 100g. of liquefied propylene and then a given amount of hydrogen wereintroduced under pressure. The mixture was maintained at 70 C. andpolymerized with stirring for one hour. The polymerization pressurereached 25-30 kg./cm. After cooling the mixture, unpolymerized propylenewas discharged. The resulting polypropylene was treated with methanol todecompose the catalyst and was then dried in vacuum, whereby the polymerwas brought into a powdery state. The results obtained are shown inTable 3. (Example 4 set forth in Table l was also effected 70 C. for onehour. The resulting polymer was treated 55 according to this example.)

TABLE 3 Example 1 2 3 4 5 6 7 8 9 10 11 Titanium trichloride (mmol.) 0.5 0. 5 0. 5 0. 5 0. 5 0. 75 0. 75 0. 75 0. 75 0. 75 0. 75 PDTDM (mmol.)0. 5 0. 5 0. 5 0. 5 0. 5 0. 75 0. 75 0. 75 0. 75 1. 5 1. 5 Diethylzlnc(mmol.) 0. 75 0. 75 1. 0 1. 0 1. 0 1. 5 1. 5 1. 5 1. 5 1. 5 1. 5Triethylamine (mmol.) 0.75 0. 75 1.0 1.0 1. 5 1. 5 1. 5 1. 5 1. 5 2. 252. 25 Hydrogen (mol.) 0. 014 0. 021 0. 0022 0. 0045 0. 0022 0. 0022 0.0045 0. 009 0. 01s 0. 0022 0. 0045 (1A 285 512 460 490 390 400 358 247556 436 Molecularweight 9x10 152x10 132x10 199x10 204x10 140x10 113x10718X10 252x10 x10 LI. (pereent).. 82 90.1 89 84.9 91. 87 6 86.5 s4 s9 483.5

with methanol and was then dried to obtain 17.3 g. of powderedpolybutene-l.

Example II-7 What is claimed is:

1. A process comprising homopolymerizing or cop lymerizing olefins inthe presence of a catalyst which is a mixture of a halide of titanium,vanadium or zirconium A 300 ml. autoclave was flushed with argon, andwas 70 and an organo titanium compound of the formula pressure, themixture was polymerized with stirring 75 9 wherein R is an alkyl group;and Z is (CH;),,,, in which one or more hydrogen atoms may besubstituted by an alkyl group; and m is 2, 3 or 4.

2. A process for producing polyethylene modified in molecular Weight,said process comprising polymerizing ethylene in the presence ofhydrogen and a catalyst which is a mixture of a halide of titanium,vanadium or zirconium and an organo titanium compound of the forwhereinR is an alkyl group; and Z is (CH in which one or more hydrogen atomsmay be substituted by an alkyl group; and m is 2, 3 or 4.

3. A process for producing polypropylene, said process comprisingpolymerizing propylene in the presence of hydrogen and a catalyst whichis a mixture of titanium trichloride, a dialkylzinc, an amine and anorgano titanium compound of the formula of 10 groups; and m is 2, 3 or4.

No references cited.

JOSEPH L. SCHOFER, Primary Examiner 15 EDWARD J. SMITH, AssistantExaminer US. Cl. X.R.

